This application is based upon and claims the benefit of priority from the prior Japan Patent Application No. P2002-208316, filed Jul. 17, 2002, the entire contents of which are incorporated herein by reference.
This invention relates to a structure for mounting a backrest. More specifically, the present claimed invention relates to a structure for mounting a backrest on a back frame.
A conventional structure for mounting a backrest comprises, as shown in FIG. 15, a backrest portion 101 that has a nature of cushion, an inner shell 102 as a shell of the backrest portion 101, a back support rod 104 that is mounted on the inner shell 102 with a screw 103 so as to connect the backrest portion 101 with a seat and an outer shell 105 that is mounted on a back face side of the backrest portion 101 so as to cover a connecting portion of the inner shell 102 and the back support rod 104. (Refer to FIG. 4 of Japan Laid Open No. 07-095912.)
However, since the conventional structure for mounting the backrest uses the outer shell 105, there are some problems such that a number of components is increased or a process of assembling is also increased. In addition, since the structure uses a lot of screws 103 for mounting the backrest, a process of mounting or dismounting the backrest is troublesome.
The present claimed invention intends to provide a structure that uses neither an outer shell nor or few screws so that the backrest portion can be mounted on the back frame with ease.
In order to attain the above object, a structure for mounting a backrest described in claim 1 is, in a chair comprising at least a backrest portion to support a back of a seated person and a back frame to connect the backrest portion with a seat, so arranged that the backrest portion has a pocket that covers an upper portion of the back frame, the pocket has an engaging portion that prevents the upper portion from being pulled out of the pocket by making an engagement with the upper portion of the back frame and the upper portion of the back frame is covered with the pocket and the backrest portion is mounted on the back frame by engaging the engaging portion with the covered upper portion of the back frame.
As a result, the backrest portion is mounted on the back frame by covering the upper portion of the back frame with the pocket provided on the backrest portion and engaging the engaging portion provided on the pocket with the covered upper portion of the back frame. This makes it possible to mount the backrest portion on the back frame easily without an outer shell and with a few or no screw.
Further, the structure for mounting the backrest described in claim 2 of the structure described in claim 1 is so arranged that the backrest portion comprises a frame-shaped inner shell and a bag-shaped superficial skin that wraps the inner shell and the upper portion of the back frame has a frame body comprising a portion facing to the inner shell and a portion that makes an engagement with the engaging portion. In this case, the backrest portion can be supported in a stable condition by overlapping the inner shell and the frame body of the back frame.
Further, the structure for mounting the backrest described in claim 3 of the structure described in claim 1 or 2 is so arranged that the engaging portion is arranged at an opening edge portion of the pocket. In this case, the pocket is prevented from being rolled and from being unstrained or wrinkling.
Further, the structure for mounting the backrest described in claim 4 of the structure described in one of claim 1 through claim 3 is so arranged that the backrest portion has a bent portion that is formed to protrude toward a lumbar of the seated person, the back frame has a movable member that is so arranged to move relatively to the back frame, a lower end side of the backrest portion is mounted on the movable member and a protruding amount of the bent portion can be adjusted by moving the movable member. In this case, a lumbar support mechanism that can adjust a protruding amount of the bent portion that is formed to protrude toward the lumbar of the seated person can be constructed.